Ch01 Lecture Presentation

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© 2013 Pearson Education, Inc.

Essentials of GENETICS

William S. Klug

Michael R. CummingsCharlotte A. Spencer

Michael A. Palladino

Lecture Presentations by

Kiran Misra

Edinboro University

Eighth Edition

1 Introduction

to Genetics




Chapter 1 Contents

1.1 Genetics Has a Rich and Interesting History1.2 Genetics Progressed from Mendel to DNA in Less Than a

Century

1.3 Discovery of the Double Helix Launched the Era of

Molecular Genetics1.4 Development of Recombinant DNA Technology Began the

Era of Cloning

1.5 The Impact of Biotechnology Is Continually Expanding

1.6 Genomics, Proteomics, and Bioinformatics Are New andExpanding Fields

1.7 Genetic Studies Rely on the Use of Model Organisms

1.8 We Live in the Age of Genetics




Chapter 1 Introduction

In December 1998, Iceland granted deCodeGenetics, a biotechnology company, a license to

create and operate a database drawn from medical

records of all its 270,000 residents until 2012.

A combination of medical-genealogical information

forms a powerful resource available exclusively to

deCode.

This is a real example of the increasingly complex

interaction of genetics and society.




Chapter 1 Introduction

Similar large-scale projects have been generated inGreat Britain, Estonia, Latvia, the Kingdom of Tonga,and other countries.

In the United States, smaller-scale programsinvolving tens of thousands of individuals areunderway.

These databases will be used to search for genes

that control human diseases. It is important to address the ethical questions

surrounding an emerging technology as theinformation is gained.




1.1 Genetics Has a Rich and Interesting History




Section 1.1

Archaeological evidence documents thousands ofyears of domestication and cultivation of plants by

artificial selection.

– 8000 to 1000 B.C.: domestication of horses, camels,oxen and wolves; maize, wheat, rice, and date palm

The Hippocratic School of Medicine (500 –400 B.C.)

and Aristotle (384 –400 B.C.) attempted to explain

heredity using the concept of active “humors” and

vital heat.




Section 1.1

300 B.C. – A.D. 1600: Few significant ideas were putforward to explain heredity.

1600 –1850: The Dawn of Modern Biology

– William Harvey (1600s): Theory of Epigenesis

– An organism develops from a fertilized egg throughdevelopmental events, transforming the egg into anadult.

– Schleiden and Schwann (1830): The Cell Theory

– All organisms are composed of cells derived frompreexisting ones.




Section 1.1

Louis Pasteur disproved the idea of spontaneousgeneration.

– Creation of living organisms from nonliving

components

Charles Darwin’s travels on the HMS Beagle

provided him geological, geographical, and

biological observations that helped formulate his

theory of natural selection.




Section 1.1

Darwin published his ideas on evolutionary theory inThe Origin of Species (1859).

Existing species arose from other ancestral speciesby descent with modification.

Natural selection was the driving force forevolutionary change.

Evolution was independently proposed by Alfred

Russel Wallace. Darwin had no understanding of the mechanism

involved.

Mendel (1866) offered an explanation using peas.




1.2 Genetics Progressed from Mendel to DNAin Less Than a Century




Section 1.2

Mendel worked with peas and used quantitative datato show that traits are passed from parents tooffspring in predictable ways.

– Each trait is controlled by a pair of genes that separate

during gamete formation.

Mendel published his findings (1866) offering ageneral model of how traits are passed, but his work

was largely unknown. Mendel’s work was “rediscovered” around 1900 and

forms the foundation of genetics.




Section 1.2

Advances in microscopy have identifiedchromosomes (Figure 1-2) and establish that mosteukaryotes are diploid (2n, two sets ofchromosomes).

– Human diploid number: 46 (Figure 1-3)

Eukaryotic cells undergo two types of cell division:

– Mitosis: Two resulting daughter cells receive a diploid set of chromosomes (Figure 1-4).

– Meiosis: Resulting cells (gametes) receive only halfthe number of chromosomes (haploid, n).




Section 1.2

The chromosomal theory of inheritance (Sutton andBoveri) states that inherited traits are controlled by

genes residing on chromosomes.

Genes are transmitted through gametes.

This transmission maintains genetic continuity from

generation to generation.




Section 1.2

Alternate forms of a gene are called alleles. – That is, alleles for various eye colors.

Variations in genes/alleles (DNA sequences) are the

result of mutations.

Mutations are the source of genetic variation.

The set of alleles for a given trait is called the

genotype.

The expression of the genotype produces an

observable trait or phenotype.




Section 1.2

DNA (nucleic acid), not protein, is the carrier ofgenetic information

– Research of Avery, MacLeod, and McCarty: 1944






Section 1.3

The structure of DNA was described by Watson andCrick (1953).

DNA is an antiparallel, double-stranded helix.

– Monomer: nucleotide

– Sugar bonded to a phosphate and four bases

– Adenine, cytosine, guanine, and thymine

– These nucleotides form A=T and G=Ccomplementary base pairing across the helix (Figure1-7).

Figure 1 7




Figure 1-7




Section 1.3

RNA (nucleic acid) is similar to DNA, except that:

– it is usually single-stranded.

– it has adenine, cytosine, and guanine but has uracil

(U) in place of thymine (T).

– the sugar in RNA nucleotides is ribose instead of

deoxyribose.




Section 1.3

Transcription is the process by which theinformation on a DNA strand is transcribed into amessenger RNA (mRNA).

– Transcription occurs in the nucleus.

The mRNA moves into the cytoplasm where it bindsto a ribosome.

The information in the mRNA is translated into aprotein (translation).

This is known as the central dogma of genetics(Figure 1-8).

Figure 1-8




Figure 1 8






Section 1.3

Once a protein is made, its action or location in acell plays a role in producing a phenotype.

– Enzymes are the largest category of proteins.

– Other proteins include hemoglobin, insulin,connective tissue, actin, and myosin.




Section 1.3

Mutations altering a gene may modify, alter, or eveneliminate the protein’s usual function and cause an

altered phenotype.

– Sickle-cell anemia results from a mutation in thegene encoding B-globin, resulting in an amino acid

substitution (Figure 1-9).

– Sickle-shaped red blood cells are deformed and

fragile and break easily, leading to a whole series ofphysical and physiological problems (Figure 1-10).




1.4 Development of Recombinant DNATechnology Began the Era of Cloning




Section 1.4

In the 1970s researchers discovered restrictionenzymes in bacteria that cut viral DNA at specificsites.

With the use of vectors, restriction enzymes have

allowed the advent of recombinant DNA andcloning.

Recombinant technology has given rise to the

biotechnology industry, which is a major contributorto the U.S. economy.




1.5 The Impact of Biotechnology IsContinually Expanding




Section 1.5

Biotechnology has been used for the geneticmodification of crop plants for:

– increased herbicide, insect, and viral resistance.

– 85% of U.S. corn plants

– 95% of U.S. soybean plants

– nutritional enhancement.

Some genetically altered traits in crop plants are

shown in Table 1.1.




Section 1.5

Biotechnology has also been used for the geneticmodification of animals (Figure 1-11).

– Makes possible the production of even dozens or

hundreds of offspring with desirable trait

– Transgenic animals are used to synthesize

therapeutic proteins.

– Anticlotting protein from milk of transgenic goats

–Clinical trials underway to treat several diseases,

including emphysema

Table 1.1







Section 1.5

Gene therapy and genetic testing have hadprofound impact on the diagnosis of genetic

diseases.

The molecular basis for hundreds of geneticdisorders is known (Figure 1-12).

Biotechnologically derived prenatal diagnosis of

“carriers” is currently available for more than 100

inherited disorders.

Figure 1-13







1.6 Genomics, Proteomics, and BioinformaticsAre New and Expanding Fields




Section 1.6

Genomics analyzes genome sequences to studythe structure, function, and evolution of genes andgenomes.

Proteomics identifies a set of proteins present in

cells under a given set of conditions and studiestheir function and interactions.

Bioinformatics develops hardware and software

for processing nucleotide and protein data.




1.7 Genetic Studies Rely on the Use of

Model Organisms

S i 1 7




Section 1.7

Model organisms for genetic study meet thefollowing criteria:

– Easy to grow

– Short life cycle

– Produce many offspring

– Genetic analysis straightforward

S i 1 7




Section 1.7

All life has a common origin, and genes with similarfunctions in different organisms are similar in

structure and DNA sequence.

The genetics of model organisms can be applied tohumans for understanding and treating human

diseases.

S ti 1 7




Section 1.7

By transferring genes between species,scientists have developed models of human

diseases in organisms ranging from bacteria to

fungi, plants, and animals (Table 1.2).

The gene transfer approach is being used to

study many human neurological disorders

including

– Huntington Disease

– Alzheimer’s Disease

Table 1.2







1.8 We Live in the Age of Genetics



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